The present invention relates to a power circuit device, and more particularly to a power circuit device suitable to be suitably used for an image forming apparatus such as an electrophotographic copying apparatus or the like.
A power circuit in an electrophotographic copying apparatus generally includes elements which emit heat more or less (hereinafter referred to heat emitting elements) such as resistors, transistors, diodes and the like. Thus, radiator plates are often required.
The power circuit is housed in a limited space in an electrophotographic copying apparatus. Accordingly, the power circuit is apt to be designed such that the printed circuit board thereof is reduced in area. To enhance the radiation effect, the radiator plates are suitably disposed on the printed circuit board at required positions thereof, and the heat emitting elements are attached to the radiator plates. As a result, the power circuit device may be reduced in volume, and the radiation effect may be improved.
A conventional typical power circuit device is shown in FIG. 5. In FIG. 5, radiator plates 2, 3, having great heat capacity, are respectively disposed at both lateral sides of a printed circuit board 1. Some heat emitting elements 4a, 4b, 4c, etc., such as power transistors and the like, are attached to the radiator plates 2, 3.
As shown above, the conventional power circuit device has been designed based on the concept that it is the best to reduce the entire volume of the power circuit device to make the same in a small size, thereby to enhance the general-purpose properties thereof.
In designing the power circuit, when it is desired to design an efficient circuit, the printed circuit board is generally made in the form of a regular square or a rectangle, close to a regular square. When incorporating such a power circuit device in an electrophotographic copying apparatus, a custom space for housing the power circuit device should be formed in the apparatus, since the power circuit device is made in the form of a cube or a rectangular parallelpiped, close to a cube, even though the power circuit device is made in a small size. However, the electrophotographic copying apparatus includes a number of mechanisms required for image forming processing. It has been, therefore, difficult to provide in a electrophotographic copying apparatus a large space for housing the power circuit device, with the layout of such image forming processing mechanisms taken into consideration. To obtain a space for housing the power circuit device in the electrophotographic copying apparatus, it is inevitably required to increase the volume of the electrophotographic copying apparatus. This presents the problem that the apparatus is increased in size.
In this connection, it may be proposed to externally attach the power circuit device to the electrophotographic copying apparatus. For example, a projecting portion 5, as shown in FIG. 6, may be disposed at the back of an electrophotographic copying apparatus 6. To improve the radiation effect of the power circuit device, the projecting portion 5 is provided in the wall surface thereof with radiating slits 7.
The arrangement including such a projecting portion 5 presents the problem that the electrophotographic copying apparatus requires a wider installation space in a room.
In the power circuit device, the radiation effect should be enhanced even though the entire volume of the device is small. Accordingly, thick radiator plates 2, 3 having great heat capacity should be disposed. With the increase in the number of heat emitting elements, the capacity or volume of the radiator plates must inevitably be increased. Accordingly, the radiator plates become expensive, resulting in an increase in cost of the power circuit device.
The electrophotographic copying apparatus incorporates complicated image forming processing mechanisms. However, some gaps are locally present in the apparatus. Such gaps are generally long and narrow vacant spaces. The conventional power circuit device is made in the form of a cube or a rectangular parallelpiped, close to a cube even though it is made in a small size. Accordingly, the conventional power circuit device cannot be housed in any of these long and narrow vacant spaces.
Further, if the power circuit device is to be made slender, it is difficult to design the pattern of the printed circuit board. Accordingly, such a slender power circuit device has been conventionally regarded as a device full of faults by those who are skilled in the field of designing of power circuit devices.
Further, when the printed circuit board is long, an automatic assembling apparatus should move in a wider range for securing and wiring heat emitting elements to the printed circuit board. This results in increase in size and cost of the automatic assembling apparatus.
Thus, since the slender power circuit device has many faults and no advantages, those skilled in the art, or the persons concerned, have not taken such a device into consideration.
However, when the power circuit device is not regarded as a single device, but is considered from the viewpoint of a component element to be incorporated in an electrophotographic copying apparatus, a slender power circuit device may be disposed in the electrophotographic copying apparatus within one of the vacant spaces therein, and effectively used without requiring a special place. This results in reduction in the size of the electrophotographic copying apparatus. The inventor of the present invention has taken notice of the foregoing and, based on such a concept, he has completed the present invention.
It is an object of the present invention to provide a high-performance power circuit device which can be incorporated in apparatus within surplus spaces therein, thereby making efficient use of vacant spaces in the apparatus.